The present invention relates to processes for dehusking psyllium seeds. These processes are useful for obtaining high yields of high purity psyllium seed husk.
The seed to be dehusked by the processes of the present invention is psyllium seed from plants of the Plantago genus. Various species such as Plantago lanceolate, P. rugelii, and P. major are known. Commercial psyllium seed husk is typically obtained from the French (black; Plantago indica), Spanish (P. psyllium) or Indian (blonde; P. ovata) psyllium seeds. Indian (blonde) psyllium seed husk is preferably prepared by the present processes.
Psyllium seed husk is used in high fiber food products and/or health care products for its benefit of normalizing bowel function and laxation. In addition, recent research has demonstrated the effectiveness of psyllium seed husk fiber in reducing human serum cholesterol levels, and in controlling blood glucose levels in diabetics. Observed and anticipated growth in the markets for these psyllium husk-containing products give rise to the need for greater quantities of high purity psyllium husk. Thus, there is a need for processes for obtaining higher yields of high purity psyllium husk that are more efficient than the currently used methods.
Psyllium seed husk is typically manufactured presently by separating the seed husk from the remainder of the seed by slight mechanical pressure, for example by crushing the seeds between rotating plates or rollers. The husk is then typically purified by sieving the mixture to separate the husk from the remainder of the seed parts and/or by blowing (winnowing) the husk away from the impurities. Impurity present in the psyllium husk is predominantly dark particles which are readily visually apparent amongst the blond-colored psyllium husk; and are readily perceived as being particularly gritty during ingestion. Subsequent attempts at purifying the psyllium further, for example by sieving, are generally tedious processes which produce low yields of psyllium and/or only moderately improved purity.
Mills suitable for the processes of the present invention are known. Generally, they are characterized as being mills which produce fragmentation (i.e., the "milling") of materials through collision, including particle-particle collision (e.g., fluid energy mills) and/or particle-blunt surface collision (e.g., stud mills; ball mills), rather than having the fragmentation being caused solely by a crushing action or by scissoring, screening, abrading, shearing, or slicing actions.
Such mills have been used to mill a wide variety of materials. For example, materials such as silica gel, tungsten carbide, toner, wax, resin, fat, and mica have been milled in fluidized bed opposed jet mills; and materials such as acetyl salicylic acid, bran, sesame seeds, glucose, grains, and copper oxychloride have been milled in stud mills. Furthermore, selective grinding by fluidized bed opposed jet mills during the processing of foundry sand (to separate water glass bond or resin cement from the sand) and the cleaning of metal alloys (to separate mineral or ceramic contaminants from the main alloy) are known.
An object of the present invention is to provide processes for dehusking psyllium seeds without substantial breakage and size reduction of the non-husk core of the psyllium seed. Such processes are useful for manufacturing high yields of high purity psyllium seed husk from whole psyllium seeds. A further object is to provide processes for removing the psyllium seed husk from whole psyllium seed while avoiding breaking the core of the seed, thereby reducing contamination of the husk with non-husk seed parts (resulting in higher purity due to easier separation of husk and non-husk seed parts). Another object is to provide processes for obtaining psyllium husk and non-husk mixtures which are easily separated by density, particle size and/or shape separation methods (e.g., sieving; screening) into husk and non-husk fractions having little contamination by the other fraction's components. It is also an object to provide efficient, low energy processes for manufacturing psyllium seed husk.
These and other objects of the present invention will become readily apparent from the detailed description which follows.
All percentages and ratios used herein are by weight unless otherwise specified. Screen mesh sizes used herein are based on U.S. standards.